While trying to get my engine lined up for a timing chain replacement, I heard a click sound from the vanos/gear region. Whereas previous turns the exhaust and intake cams were withing probably 5 degrees of each other, now the exhaust is around 100 degrees off of the intake. The crank is pinned. Intake is in the correct position to lock.

Firstly, I'm curious as to what could've happen to suddenly shift the exhaust cam that much. Secondly I'm worried about what to do now. My inclination is to carry on with removing the timing chain without the exhaust cam locked, and then turn it to align it and lock it when the chain is off. Hopefully, no damage has already been done to the valves.

Any suggestions?